20-45416223-G-A

Variant names:

• chr20-45416223-G-A
• rs771087475
• NM_015937.6:c.67G>A

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_015937.6(PIGT):​c.67G>A​(p.Ala23Thr) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000831 in 1,444,218 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 13/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000083 (0 hom.)
• Consequence: PIGT NM_015937.6 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.863

Genes affected

PIGT (HGNC:14938): (phosphatidylinositol glycan anchor biosynthesis class T) This gene encodes a protein that is involved in glycosylphosphatidylinositol (GPI)-anchor biosynthesis. The GPI-anchor is a glycolipid found on many blood cells and serves to anchor proteins to the cell surface. This protein is an essential component of the multisubunit enzyme, GPI transamidase. GPI transamidase mediates GPI anchoring in the endoplasmic reticulum, by catalyzing the transfer of fully assembled GPI units to proteins. Alternatively spliced transcript variants encoding multiple isoforms have been observed for this gene. [provided by RefSeq, May 2012]

LOC107985405 (HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.16025767).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
PIGT	NM_015937.6	c.67G>A	p.Ala23Thr	missense_variant	Exon 1 of 12	ENST00000279036.12	NP_057021.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
PIGT	ENST00000279036.12	c.67G>A	p.Ala23Thr	missense_variant	Exon 1 of 12	1	NM_015937.6	ENSP00000279036.6

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000831 AC: 12 AN: 1444218 Hom.: 0 Cov.: 31 AF XY: 0.0000112 AC XY: 8 AN XY: 717054

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000109

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ExAC AF: 0.00000827 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Multiple congenital anomalies-hypotonia-seizures syndrome 3 Uncertain:1

May 23, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces alanine, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 23 of the PIGT protein (p.Ala23Thr). The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This variant has not been reported in the literature in individuals affected with PIGT-related conditions. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt PIGT protein function with a negative predictive value of 80%. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.085
BayesDel_addAF	Benign	-0.17	T
BayesDel_noAF	Benign	-0.48
CADD	Benign	18
DANN	Uncertain	0.99
DEOGEN2	Benign	0.017	T;.;.;.;.;.;.;.;.;.;.;.;.;.;.
Eigen	Benign	-0.39
Eigen_PC	Benign	-0.48
FATHMM_MKL	Benign	0.28	N
LIST_S2	Uncertain	0.88	D;D;D;D;D;D;D;D;D;D;D;D;D;D;D
M_CAP	Benign	0.0076	T
MetaRNN	Benign	0.16	T;T;T;T;T;T;T;T;T;T;T;T;T;T;T
MetaSVM	Benign	-1.0	T
MutationAssessor	Benign	0.63	N;N;N;N;.;.;.;.;.;.;.;.;.;N;.
PrimateAI	Uncertain	0.52	T
PROVEAN	Benign	-0.71	N;N;N;N;.;.;.;.;.;.;.;.;.;.;.
REVEL	Benign	0.054
Sift	Uncertain	0.012	D;D;D;D;.;.;.;.;.;.;.;.;.;.;.
Sift4G	Benign	0.17	T;T;T;T;.;.;.;.;.;.;.;.;.;.;.
Polyphen		0.0010	B;B;.;.;.;.;.;.;.;.;.;.;.;B;.
Vest4		0.19
MutPred		0.49		Gain of relative solvent accessibility (P = 0.0023);Gain of relative solvent accessibility (P = 0.0023);Gain of relative solvent accessibility (P = 0.0023);Gain of relative solvent accessibility (P = 0.0023);Gain of relative solvent accessibility (P = 0.0023);Gain of relative solvent accessibility (P = 0.0023);Gain of relative solvent accessibility (P = 0.0023);Gain of relative solvent accessibility (P = 0.0023);Gain of relative solvent accessibility (P = 0.0023);Gain of relative solvent accessibility (P = 0.0023);Gain of relative solvent accessibility (P = 0.0023);Gain of relative solvent accessibility (P = 0.0023);Gain of relative solvent accessibility (P = 0.0023);Gain of relative solvent accessibility (P = 0.0023);.;
MVP		0.48
MPC		0.12
ClinPred		0.11	T
GERP RS		2.5
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.6
Varity_R		0.12
gMVP		0.51

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs771087475; hg19: chr20-44044863;